| Abstract
| - The new N-functionally substituted azadithiolate ADT-type model complexes 2−9 have been synthesizedstarting from the known complex [(μ-SCH2)2NCH2CH2OH]Fe2(CO)6 (1). Treatment of 1 with ahalogenating agent, a mixture of PPh3 and CBr4, affords [(μ-SCH2)2NCH2CH2Br]Fe2(CO)6 (2). Furthertreatment of 2 with MeC(O)SNa gives [(μ-SCH2)2NCH2CH2SC(O)Me]Fe2(CO)6 (3). While 1 reacts withthe acylating reagent 1-naphthaleneacetyl, 2-furancarbonyl, or 2-thiophenecarbonyl chloride to produce[(μ-SCH2)2NCH2CH2O2CCH2C10H7-1]Fe2(CO)6 (4) and [(μ-SCH2)2NCH2CH2O2CC4H3X-2]Fe2(CO)6 (6,X = O; 7, X = S), the CO substitution reaction of 4 with PPh3 yields [(μ-SCH2)2NCH2CH2O2CCH2C10H7-1]Fe2(CO)5(PPh3) (5). In the presence of the esterification catalyst 4-dimethylaminopyridine (DMAP)and the esterification activator N,N‘-dicyclohexylcarbodiimide (DCC), 1 reacts with CH2(CO2H)2 to givethe unexpected single model complex [(μ-SCH2)2NCH2CH2O2CMe]Fe2(CO)6 (8), whereas reaction of 1with p-(HO2C)2C6H4 under similar conditions affords the double model complex [(μ-SCH2)2NCH2CH2Fe2(CO)6]2[1,4-(O2C)2C6H4] (9). Starting complex 1 is found to be prepared in a much higher yield byanother method, which involves reaction of NH2CH2CH2OH with the in situ formed intermediate (μ-HOCH2S)2Fe2(CO)6 from CH2O and (μ-HS)2Fe2(CO)6. The X-ray crystallographic study reveals that whilethe N-functional substituents of 1, 3, and 8 are axially bonded to their N atoms, the N-substituent of 7is equatorially bound to its N atom. The IR spectra of 3 and 7 with CF3SO3H or CF3CO2H along withtheir 1H NMR spectra with CF3CO2H or HOAc indicate that their bridgehead N atoms are protonated bystrong acid CF3SO3H and partially protonated by the medium strong acid CF3CO2H, but not by weakacid HOAc. The electrochemical properties of 2, 3, 6, and 7 are studied by CV and CA techniques,whereas 7 is further found to be a catalyst for H2 production under electrochemical conditions. A 2E2Cmechanism for this electrocatalytic H2 evolution has been proposed, which is consistent with the above-mentioned protonation study of 7.
- A new series of the N-functionally substituted azadithiolate H-cluster models is synthesized starting from [(μ-SCH2)2NCH2CH2OH]Fe2(CO)6 by functional transformation and CO substitution reactions. Three new crystal structures and the biomimetic H2 evolution catalyzed by one of the synthesized models are reported.
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